The present invention relates to a powder inhaler for administering powder by inhalation.
A number of powder inhalers are known which use different systems for introducing a dose of powder into an air stream. Typically, the powder is inhaled into the lungs of a patient in order to treat, for example, asthma.
One such powder inhaler is disclosed in EP-A-0237507. This inhaler comprises an inhalation channel and a mouthpiece comprising an air chamber and an outlet nozzle, which together define a flow path through which a stream of air is drawn during inhalation by a user. This inhaler further comprises means for introducing powder into the inhalation channel. During inhalation, air is first drawn into and through the inhalation channel so as to pick up powder. The stream of air containing powder is then drawn through the air chamber and out of the outlet nozzle of the mouthpiece.
FIG. 1 illustrates such a powder inhaler. The inhaler comprises a mouthpiece 2 comprising an outlet nozzle 4, an inhaler body 6 and a rotatable grip portion 8 for operating a dosing mechanism for providing doses of powder for inhalation. The inhaler body 6 is provided with an opening 10 which is filled with a window 12 through which an indicating wheel 42 is visible so as to provide an indication as,to the usage of the inhaler.
FIG. 2 illustrates in exploded view component parts disposed within and to the inhaler body 6. The inhaler body 6 is capped with a divider 14 which is fixed thereto. For aesthetic reasons the inhaler body 6 is an opaque moulding. The divider 14 is a transparent moulding which has a depending tongue 15, a part of which forms the window 12.
Within the inhaler body 6 are housed the component parts of the dosing mechanism. These component parts include a dosing unit 16 which comprises a member 17 having a planar surface in which a plurality of dosing means 18 are provided and a shaft 20 which extends axially from the centre of the member 17, an inhalation unit 22 which comprises an inhalation channel 24 and a storage unit 26 which comprises a storage chamber 28 for storing powder. The above-mentioned component parts of the dosing mechanism are assembled by passing the inhalation channel 24 through an opening 30 in the storage unit 26 and passing the shaft 20 through central openings 32, 34 in the inhalation unit 22 and the storage unit 26 respectively. When so assembled, the upper ends of the inhalation channel 24 and the storage chamber 28 pass respectively through first and second openings 36, 38 in the divider 14. In this way, the inhalation unit 22 and the storage unit 26 are fixed in position in relation to one another and the dosing unit 16 can be rotated relative thereto.
In this inhaler the storage unit 28 is open at the bottom such that in use powder is provided to the dosing unit 16 under the action of gravity and the inhalation unit 22 further comprises scrapers 40 which are resiliently biased against the surface of the member 17 in which the dosing means 18 are provided. In this way, as the dosing unit 16 is rotated, the dosing means 18, which in this inhaler comprise a plurality of through holes, are filled with powder by the scrapers 40. Powder is prevented from passing through the dosing means 18 by a plate (not illustrated) which is disposed beneath the dosing unit 16.
As illustrated in FIG. 2, the divider 14 further comprises supporting means 41 for rotatably supporting an indicating wheel 42. The indicating wheel 42 has a plurality of teeth 44 disposed around the periphery thereof which engage with a spiral groove or protrusion 46 on the end face of the shaft 20. The supporting means 41 is configured to align the indicating wheel 42 such that a part of the periphery thereof is disposed adjacent the inner surface of the window 12. In use, as the dosing unit 16 is rotated, the spiral groove or protrusion 46 engages with one or more of the teeth 44 on the indicating wheel 42 so as to rotate the same. In this way, by providing a coloured marking on the periphery of the indicating wheel 42, it is possible to provide the user with a visible indication at the window 12 as to the usage of the inhaler.
As illustrated in FIG. 4, the mouthpiece 2 is fixed to the divider 14. The mouthpiece 2 comprises first and second parts 48, 50, the first part 48 being the part which is gripped by the lips of a user and the second part 50 being an insert fitted within the first part 48. The second part 50 comprises a tubular section 52, which includes one or more spirally or helically shaped projections 54 that act to deflect the air drawn therethrough and thereby deagglomerate any larger particles of entrained powder, and a substantially radially-directed flange 56, which provides a surface that together with upper surface of the divider 14 defines an air chamber 58 that is in fluid communication with the inhalation channel 24 through which air containing powder is drawn on inhalation by a user.
In use, as described hereinabove, powder is transferred from the storage chamber 28 to one of the dosing means 18, and, with rotation of the dosing unit 16, the one dosing means 18 provides a dose of powder to the inhalation channel 24. In this inhaler the dosing unit 16 is rotated by rotating the grip portion 8 in the counter-clockwise sense between first and second angularly-spaced positions. For this purpose the dosing unit 16 comprises wedge-shaped elements 60 disposed around the periphery of the member 17 and the grip portion 8 comprises a resilient member (not illustrated) which is configured to engage with an axially-directed surface 60a of a respective one of the wedge-shaped elements 60 so as to rotate the dosing unit 16 by pushing the respective wedge-shaped element 60. On rotation of the grip portion 8 in the opposite, clockwise, sense between the second and the first angularly-spaced positions, the dosing unit 16 remains stationary and the resilient member is located behind the axially-directed surface 60a of the adjacent wedge-shaped element 60; the resilient member riding over an inclined surface 60b of the adjacent wedge-shaped element 60.
Although the above-described known powder inhaler functions quite adequately, powder may accumulate on surfaces in the flow path through the inhaler.
It is thus an aim of the present invention to provide a powder inhaler having a construction which is such as to reduce the possibility of powder accumulating on surfaces in the flow path therethrough.
Accordingly, the present invention provides a powder inhaler for administering powder by inhalation, comprising: a flow path defined by a plurality of surfaces through which a stream of air is in use drawn on inhalation by a user; and dosing means for providing a dose of powder to the flow path for entertainment in the stream of air; characterized in that the inhaler further comprises dislodging means for dislodging powder accumulated on a surface of the flow path downstream of the dosing means.
The present invention also provides a powder inhaler for administering powder by inhalation. comprising: a housing having a screw thread; a mouthpiece attached to the housing so as to be rotatable relative thereto; and a cap for covering at least the mouthpiece, the cap having a screw thread for engaging the screw thread on the housing; characterized in that the mouthpiece and the cap are adapted such that at least a part of the mouthpiece is rotated relative to the housing on one of screwing or unscrewing the cap, which part of the mouthpiece substantially remains in fixed position relative to the housing on the other of screwing or unscrewing the cap.
By virtue of the present invention, powder which may have accumulated on inner surfaces of the inhaler is dislodged from those surfaces prior to the next inhalation. Powder is thus prevented from accumulating within the inhaler beyond a single use. In this way, any variation in the dose of powder delivered is limited to the amount of powder retained after a single use. This amount will, however, be very small and relatively insignificant.
In addition, by configuring the inhaler such that the mouthpiece is rotated automatically when the cap is removed, it is not necessary to rely upon the user to remember to rotate the mouthpiece prior to each inhalation.
The powder inhaler of the present invention may be used with any suitable form of powder, including powders introduced into the air stream in the raw state or as conglomerate, micronised or ordered mixture particles. Furthermore, the active ingredient or ingredients of the powder may be diluted with one or more substances such as lactose and may include substances for the treatment of various conditions, not necessarily respiratory conditions. Indeed, the powder can include genetic material and need not be restricted to human use only.
Medicaments suitable for administration by the powder inhaler of the present invention are any which may be delivered by inhalation and include for example xcex22-adrenoreceptor agonists, for example, salbutamol, terbutaline, rimiterol, fenoterol, reproterol, adrenaline. pirbuterol, isoprenaline, orciprenaline, bitolterol, salmeterol, formoterol, clenbuterol, procaterol, broxaterol, picumeterol, TA-2005, mabuterol and the like, and their pharmacologically acceptable esters and salts; anticholinergic bronchodilators, for example, ipratropium bromide and the like; glucocorticosteroids, for example, beclomethasone, fluticasone, budesonide, tipredane, dexamethasone, betamethasone, fluocinolone, triamcinolone acetonide, mometasone and the like, and their pharmacologically acceptable esters and salts; antiallergic medicaments, for example, sodium cromoglycate and nedocromil sodium; expectorants; mucolytics; antihistamines; cyclooxygenase inhibitors; leukotriene synthesis inhibitors; leukotriene antagonists; phospholipase-A2 (PLA2) inhibitors; platelet aggregating factor (PAF) antagonists and prophylactics of asthma; antiarrhythmic medicaments; tranquilisers; cardiac glycosides; hormones; antihypertensive medicaments; antidiabetic medicaments; antiparasitic medicaments; anticancer medicaments; sedatives; analgesic medicaments; antibiotics; antirheumatic medicaments; immunotherapies; antifungal medicaments; antihypotension medicaments; vaccines; antiviral medicaments; proteins; polypeptides and peptides, for example, peptide hormones and growth factors; polypeptide vaccines; enzymes; endorphines; lipoproteins and polypeptides involved in the blood coagulation cascade; vitamins; and others, for example, cell surface receptor blockers, antioxidants, free radical scavengers and organic salts of N,Nxe2x80x2-diacetylcystine.